Doc’s frame

time

All she wants in the universe is to get back home to her. Yet she knows that the faster she travels, the less likely they’ll ever see each-other again. But instinct is a powerful thing and her hand hovers trembling over the accelerator slide. Sweat on her forehead. Teeth grinding. Space and time zipping by outside the ship. She yanks her hand away and screams in agony.

Relativity’s a bitch.

That’s what she’d said to Wen that night in Digby’s on Lunar 9. She was batting the virtual ping-pong ball back and crack against the projector wall, trying not to look at Wen and blaming the moisture in her eyes on the bar’s dodgy air purifier. The grinding audio loop jangling up from the floor, loosening her knees.

“You’ve lost me, Doc,” sighed Wen, rolling her overacting eyes.

“Don’t make fun,” Doc pleaded.

Wen sidled up to her, a clear foot shorter, and pressed her forehead against Doc’s shoulder. The scent of tea tree from her shaven scalp. The warmth of her, a welcome relief from the recycled air chilling the base. Doc daren’t look down at her.

“Okay,” conceded Wen and backed away. “Explain again.”

Doc caught the ball mid-air. “See this? It’s a particle of light. A photon.”

“Actually, it’s a hard-light projection, brought to you by the good people at Nintendo.” Wen’s dropped shoulder and jaunty hipped stance. Elliptical eyes liquefied by too much chemistry. Another shot teetering between her thumb and forefinger.

“Smart ass,” diagnosed Doc and gazed at her for far too long. Did she know that Doc loved her? How old is Wen now?

“You’re making me think too hard.” Wen tossed the shot down her gob and signalled over to Digby. “Bring more.”

Doc balanced the laser ball in her palm, a wizard conjuring something demonic. “Imagine this is a photon. A speck of light that, no matter how you’re moving, where you are, what equipment you’re using to measure it, obeys just one law.”

“Don’t shit where you shine.”

“Best practice maybe, not a law. No, this speck of light must appear to move at the speed of light to all observers.”

“See, I never got that. Sounds like witchcraft.” Digby brought Wen another shot. She promptly made it disappear. Invited Digby back in five minutes.

“It’s just the way the universe works,” said Doc. “Imagine this ping-pong game is a light clock.” She batted the ball back and forth against the projector wall. Ping, crack, pong. “We’re both measuring the same amount of time for the ball to bounce back and forth.”

“Obviously,” huffed Wen. “Speed equals distance divided by time.”

“Right.” Ping, crack, pong. “But one side of that equation can’t change.”

“Speed of light. Three million metres per second.”

“I’m impressed.”

“Not just a glass rack,” said Wen and balanced the empty shot glass on her head.

“So imagine when my papers come through and I’m shipping off to the Ort Station next month.”

Wen pantomimed a cry face and wiped invisible tears from her eyes. The glass dropped off her head and resisted shattering, as per-design.

“Exactly. So, you’re at rest down here at Digby’s watching me fly away at a constant velocity of… I dunno…”

“A thousand kilometres per second.”

 Ping, crack, pong.

“Fine. Doesn’t matter. And I’ve got this light clock going back and forth, just like now, and, just like now, we both measure the speed of the ball.”

“We both measure it travelling at the speed of light.”

 Ping, crack, pong.

“Right. But I’m on the ship so I measure the distance the ball travels to be really short compared to your measurements.”

“Huh?”

“Think about it,” said Doc, getting short on breath. Ping, crack, pong. “Like on any spaceship or aeroplane, I’m not especially aware that I’m moving once I get going. It could be space moving around me for all I know”—ping, crack, pong—“so I just measure the ball as travelling the short distance to the wall and back again.”

“Digby, I’m gonna need another drink!” cried Wen, without humour.

“Meanwhile, back at relative rest in Digby’s, you’re looking through a telescope and seeing the ball travel a lot farther than I’m seeing it travel.”

“Right,” said Wen, rubbing her sozzled eyes into focus. “Because I see the ball moving to the wall and back again, but I also see it travelling away at a thousand kilometres per second.”

 Ping, crack, pong.

“It travels farther according to you. Exactly. But, if I’m measuring the ball moving a short distance, back and forth, in the same time-period as you’re measuring the same ball moving a really long distance…”

Digby brings Wen a drink and she glugs it unceremoniously.

Ping, crack, pong.

“Then logic states that the ball you’re measuring is moving a lot faster than the ball I’m measuring, because it travels a greater distance in the same amount of time.”

“No,” grumbled Wen. “Because it’s the same ball, and the speed of light appears the same to all observers.”

“Precisely,” said Doc, plucking the ball mid-flight. “So, if relative speed can’t change in the equation, then only relative time and distance can change to make sure we measure the same speed of light.”

“What are you telling me, Doc?”

Doc bit her lip. Looked someplace else. “I’m saying, the faster I travel compared to you, the slower time moves for me. My weeks. Your years.”

“All to make sure we measure lightspeed the same?”

Doc shrugged apologetically and a traitor tear tumbled down her cheek.

Wen barged in close and clutched her tight. “When will you be back, Doc?”

“There’re different answers for each of us.”

She remembers Wen sobbing against her chest.

Here, now, she paces the control room and glances nervously at the console and the accelerator slide. Everything inside her wants to push that stick forward, faster, faster, home to Wen and Lunar 9. But the faster she goes, the older Wen gets, until…

 Ping, crack, pong.

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